I do single infusion batch sparge in a 10 gal. Rubbermaid cooler, fitted with a stainless braided hose. I have a traceable thermo, and I generally mash at 154-155F for 1 hr. I have tried mashing out, though I don't usually do it. I have sparged with one volume, and multiple equal volumes. I have sparged with all 168-170F H20, and I have tried Higher temp water for the first sparge. I have checked my thermo, and there is no way it could possibly be more than 1 deg. off.

It doesn't matter whether m recipe calls for 8lbs of grain, or 15#, my OG is always between 1.040-050.

Yes, I have checked my hydrometers, they are both dead on, and yes, I do comp for temp.

I have read a lot about this subject, both on this forum, and alsewhere, and the research is what leads me to believe that the crush might be the problem.

Right now, I would kill for 70% eff.

__________________I plan on living forever. So far, so good! - unknown.

Sea, I'd almost be willing to bet the cost of the mill that your eff will increase as a result of getting a BC or a Crankandstein. If you're not milling your own grains, you're not getting your money's worth out of your grain.

Honestly, buying a mill was one of the best things I have done for my brewing. Not only can I buy bulk grains and save, but I get very good efficiency constantly, and consistency is important in brewing. My efficiency jumped up from 60% to 80% when I started milling my own grains.